ABB S273-K25 Pro M Miniature Circuit Breaker

The ABB S273-K25 is a 3-pole miniature circuit breaker (MCB) from the System pro M compact® series, engineered for overcurrent and short-circuit protection in AC electrical systems. Rated at 25 A with a K tripping characteristic suited for circuits exhibiting higher inrush currents, this device delivers dual-mechanism protection: thermal tripping for overload conditions and magnetic tripping for short circuits. Fast breaking time of 2.5–3.5 msec ensures rapid fault isolation. Operating across 230/400 V AC with interrupting capacity to 15 kA per IEC/EN 60947-2 and 10 kA per UL 489, the S273-K25 provides reliable protection across residential, commercial, and industrial installations. Toggle actuation, finger-safe screw terminals accepting conductors from 0.75 mm² to 25 mm², and contact position indication (red/green CPI) enable intuitive operation and visual confirmation. Current-limiting technology and dual-function terminals supporting simultaneous busbar and cable connections simplify installation and retrofit flexibility. The unit mounts directly to DIN rail and operates reliably across −25 °C to +55 °C. R.I.Na. naval certification available.

– Technical Specifications

• Manufacturer: ABB
• Model: S273-K25
• Poles: 3
• Current Rating: 25 A
• Voltage Rating: 230/400 V AC (typical 277/480 V)
• Frequency: 50/60 Hz
• Interrupting Capacity: 15 kA (IEC/EN 60947-2), 10 kA (UL 489/CSA 22.2 No. 5)
• Breaking Capacity: Up to 25 kA
• Tripping Characteristic: K
• Fast Breaking Time: 2.5–3.5 msec
• Conductor Compatibility: 0.75 mm² to 25 mm²
• Operating Temperature: −25 °C to +55 °C

– Key Features

• Delayed thermal and magnetic tripping mechanisms
• Current limiting for fault suppression
• Red/green contact position indication
• Captive screws and finger-safe terminals
• Dual-function terminals for busbar and cable connections
• DIN rail mounting with lower-side mounting clip
• Toggle actuator with screw terminals

– Typical Applications

• Residential, commercial, and industrial circuit protection
• Systems requiring coordinated overload and short-circuit defense
• High inrush current environments (K characteristic)
• Naval installations (R.I.Na. rated)

– Compatibility & Integration

Fully compatible with System pro M compact® accessory ecosystem. Retrofit-ready for shunt trips, auxiliary contacts, trip contacts, and undervoltage release modules. Dual-function terminals eliminate need for additional connection pieces. Top or bottom busbar feed configuration supported. Compliant with UL 489, IEC/EN 60947-2, CSA 22.2 No. 5, and UL 1077.